THE SIGNIFICANCE OF THE FOODSTUFFS 693 



urine. The loss of salts to the body will therefore be in direct proportion to 

 the degree in which the animal is living at the expense of its own tissues. 



ACCESSORY FOOD SUBSTANCES OR FOOD HORMONES 



If we feed an animal on a mixed diet containing proteins, fats, carbohy- 

 drates and salts in the proper proportions but in a state of purity, e.g. a 

 mixture of caseinogen, starch, sugar, salts and lard, we find that the animal 

 becomes ill, ceases to grow if a young animal, and finally dies. This is due 

 to the fact that practically all fresh foods contain small traces of substances 

 whose chemical nature has not been determined, but which are essential 

 for the utilisation of the food, for the maintenance of health, and for 

 the production of growth. These substances are destroyed by prolonged 

 heating or exposure to an alkaline medium, or often by simple drying of the 

 tissue in which they exist. Different accessory substances are contained 

 in different -foods or in different parts of the same food. Thus, for instance, 

 in races whose staple diet consists of rice, prolonged feeding with polished 

 rice i. e. rice in which the husks have been removed leads to the production 

 of the disease known as beri-beri. This is distinguished by the occurrence 

 of pains, weakness in the limbs, loss of sensibility in the skin, oedema, 

 and heart weakness. A similar disease in which the affection of the nerves 

 (polyneuritis) is the main disorder may be produced by the same means 

 in fowls or pigeons. If wh$le rice be eaten this disease does not occur and 

 the disease may be cured by adding the polishings i. e. the part of the 

 rice grain which has been removed to the polished rice before eating. It is 

 evident that some substance is present in the outer layer of the rice grain 

 which is essential to the normal nutrition of the body. The same substance 

 occurs in the husks and germ of wheat, in yeast, and in smaller quantities 

 in various vegetables and milk. 



Another ' deficiency disorder ' viz. scurvy has been long known and 

 described. It occurs usually when bodies of men are cut off for a long 

 time from fresh food, especially vegetables. Its main symptoms are weak- 

 ness, skin disorders, small haemorrhages under the skin, haemorrhage from 

 the gums and other mucous membranes. Scurvy is prevented or cured by 

 the administration of fresh food, especially that belonging to the crucifer 

 order, and of fruit juices, the best being juices of oranges and lemons. 



It seems that the normal process of growth in a young animal is 

 dependent on the existence of another accessory substance which is soluble 

 in fat and exists in considerable quantities in milk and milk fat (butter). 

 It is also present in other animal fats, but not in lard. It is probable that 

 this substance is present also in fresh green vegetables, and is taken by the 

 animal with its food and deposited in the fat of its tissues or excreted with 

 the fat of the milk. The absence of the substance in lard may be due to the 

 fact that pigs are fattened not as a rule on green vegetables, but on grain, 

 especially maize; further investigations are necessary on this point. In 

 the absence of this substance growth may cease. Its deficiency may lead 

 to the production of rickets, a disease of young children characterised by 



